Propioni

Propioni, in a chemical sense, refers to propionic acid (propanoic acid) and its derivatives, including salts such as sodium propionate and calcium propionate. Propionic acid is a small, colorless carboxylic acid with three carbon atoms; its propionates are widely used as preservatives and in various industrial applications. The acids and salts have distinct odor and irritant properties, with the acid form being more corrosive than its salts.

Propionic acid occurs in nature as a metabolite produced by certain bacteria, including Propionibacterium species, notably during the fermentation of dairy products like Swiss cheese. In the human body, propionate is produced by gut microbiota from dietary fiber and certain amino acids and is also used industrially. Metabolically, propionate is activated to propionyl-CoA, carboxylated to D-methylmalonyl-CoA by propionyl-CoA carboxylase (biotin-dependent), and then converted to succinyl-CoA via methylmalonyl-CoA mutase (vitamin B12-dependent). Succinyl-CoA enters the tricarboxylic acid cycle and can contribute to gluconeogenesis in the liver.

In food and industry, propionates are used primarily as preservatives to inhibit molds and some bacteria. Calcium propionate is common in bread and baked goods, while sodium propionate appears in dairy products and other foods. They are generally recognized as safe at approved use levels; however, the acid form is corrosive and may irritate skin, eyes, or the respiratory tract upon exposure.